Well, sometimes I get a bunch of parts. In the case of these parts, I wanted a sample set of exhaust logs. The seller was offering a bunch of parts. I offered to buy just the logs, and he could sell the rest separately. He sold me the logs, but sent everything. I offered to send these back kalong with some other items that came with the logs), but he responded that he wanted some particular parts I had. So, I sent him the parts he wanted.
Sometimes, people show up, looking for particular things. They leave exchange parts...or not. A few days ago, I found a box of parts in my carport. No name, but I think I know whom. When I had my '86 Fiero, I accumulated a bunch of parts for it, but sold it without most of the parts. I later gave away the GT wheels, but people are still sending me brown steering wheels and things. My current Fiero has a grey interior, so the parts are of no help to me now.
I have also found that I can often trade people for things they will not sell. I had a factory power steering unit, for a while. People will trade almost anything for that.
Research for the newsletters has caused me to accumulate lots of Fiero parts. Some of these parts go back and forth betwen myself and other people. A headlight motor, for example, went to a guy in another state, for testing. Eventually, I'll get it back. I no longer own a Gen 1 Fiero, so the motor does not help me. I had a brand new distributor. My Fiero does not use a distributor, but I needed pics. Someone grabbed the distributor, the other day. Eventually, something will show up in its place.